"The economic implications for us in a withdrawal from the European Union are very profound, costing us over a period of ten years anything in the region of £7-8bn and possibly even more," Mr McGuinness told a press conference.

'Strongest representation'

"There is alarm in the north of Ireland among the business community, among the community and voluntary sector, among our universities, among our agri-food industry and there is grave concern about the prospect that whatever is said about the common travel area being protected.

"It's very difficult to see how it can be protected in the aftermath of the debate that was held mostly in England around the whole issue of immigration and which effectively won that vote for the racists within UKIP and the loony, right-wing of the Tory party."

Image caption
A press conference was held following the British-Irish Council (BIC) meeting in Cardiff

First Minister Arlene Foster said suggestions there could be a poll on Irish unity following the UK vote to leave the European Union were "not helpful".

"There have then been denials from Micheál Martin and people like that to say that actually they weren't calling for a border poll, they were just thinking about it in a different context," she said.

"That's all very well at summer schools and whatever - I have to deal with reality, I have to be prepared for the people of Northern Ireland moving forward in this new era."